CHICAGO – The wind was blowing in at 14 mph at the start of yesterday’s game. So you’d have to hit a ball pretty hard to get it out of Wrigley Field.

But when Heath Bell threw his 11th pitch to Derrek Lee in the bottom of the 10th inning, Bell was positive it wasn’t coming back.

With the game tied, Lee was the first batter for the Cubs in that frame. On a 3-2 count, Bell threw five straight fastballs, and Lee fouled off all five.

Then Bell threw a sixth fastball. Lee didn’t foul it off.

“When I threw the pitch and I saw it tail back over to the middle and he hit it, I knew,” Bell said. “It wasn’t like, oh, maybe that’s got a shot. I knew that was going to be gone.”

It was. Lee’s blast sailed through the wind and landed in the left-field stands for a walk-off homer and a 4-3 Mets loss.

“He had to hit it like he did,” catcher Mike Piazza said of Lee.

The Mets started this six-game road trip well, winning the first two in Milwaukee.

But they closed it by dropping three of four, and though there’s obviously nothing wrong with a 3-3 road trip, it doesn’t sparkle quite as much as a 4-2 journey would have.

“It would have been nice to finish up for our off-day with a win,” Willie Randolph said, “but 3-3, we’ll take it and go on home.”

It’s tough to pin yesterday’s loss on Bell, especially because of how the ninth inning went. With the game tied 3-3, Bell entered with one out and the bases loaded, courtesy of handiwork by Mike DeJean and Dae-Sung Koo.

Bell escaped danger by getting Neifi Perez to hit into a 1-2-3 double play to end the inning. So it was with good reason that Bell got plenty of support after surrendering the walk-off shot an inning later.

“Everybody gave me a pat on the back,” Bell said, “and basically said, ‘If it wasn’t for you, we wouldn’t have had the chance to go back out there. Keep your head up and just learn from this.’ ”

The Mets also can thank Eric Valent for extending the game. Trailing 3-2 in the ninth against Cubs closer Ryan Dempster, the Mets put runners on first and third with two outs.

Pinch hitting, Valent lined an opposite-field RBI single to left to tie the game.

The Mets took an early 2-0 lead thanks to Victor Diaz’s two-run double off the right-field wall in the second. But Victor Zambrano couldn’t hold it, allowing three runs in the bottom half of the frame.

With one out in the second, Zambrano hit Jerry Hairston, then watched Henry Blanco bloop a single to center to put runners on first and second. Zambrano then balked, threw a wild pitch that scored Hairston, and walked pitcher Mark Prior.

The Cubs tied it when Corey Patterson grounded to Doug Mientkiewicz at first. Mientkiewicz stepped on the base and fired home, but his throw short-hopped Piazza and was to the first-base side of home, allowing the tying run to score. Perez followed with an RBI single to center, making it 3-2.